In some models of 2-in-1 laptop (personal computer (PC)) systems, a tablet and a keyboard dock are equipped with batteries, respectively. Every display-related function is on the tablet side. Therefore, in a case where the tablet is detached from the keyboard dock, it is impossible to easily see the capacity of the battery by only the keyboard dock. For this reason, it is demanded to make it possible to easily perform battery capacity display in a single keyboard dock. However, any means for realizing that demand is not known.